Research Of The Maturity In The Lower Silurian Longmaxi Shale,South China

Lower Silurian Longmaxi formation is the main set of shale gas in Southern Sichuan.It makes difficult to reconstruct the thermal history of early Palaeozoic.In this project,the relationship between the degree of aromatization and Ro was studied by means of Micro Fourier transform infrared(FTIR)spectroscopy,the relationship between the evolution of aromatization index-Ro was established to characterize the maturity of Silurian shale.Geological time-temperature model was established on the basic of the burial history and temperature history of typical wells.During the process of subsidenceburial-uplift,the Silurian shale has undergone a process of(rapid)warming-cooling(slow)warming-constant temperature-(rapid)cooling.The values of Ro was corrected and the current maturity of Silurian shale was determined according to the time-temperature chemical kinetics paint of vitrinite reflectance.The maturity of Longmaxi shale has reached 2.86%~2.96%,which is in the high-over maturity stage.Longmaxi shale in Fuling entered the oil generation threshold in Early Devonian,entered the oil-generation peak in Early Triassic-Middle Jurassic,entered the gas-generation in Early Cretaceous,and reached the overmature-dry gas phase in Late Cretaceous.It is of great significance to characterize the maturity of the Silurian shale in the Silurian,and the accurate characterization of the maturity and evolution of the shale is the basis for the development of shale gas exploration.